for Sustainable Transportation
sustainable
transportation
fuel:
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an inexhaustible fuel supply…
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fuel that doesn’t harm the
environment…
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domestically produced fuel.
biomass:
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abundant, renewable, domestically
grown source of energy that can be
converted into transportation fuel.
Sustainable fuels made from biomass
T
biofuels:
■
sustainable transportation fuel
made from biomass.
he word biomass refers to all the Earth’s vegetation and many products
and coproducts that come from it. Biomass is the oldest known source
of renewable energy—humans have been using it since we discovered
fire—and it has high energy content. Domestic biomass resources include
agricultural and forestry residues, municipal solid wastes, industrial wastes,
and terrestrial and aquatic crops grown solely for energy purposes.
Biomass is an attractive energy source for a number of reasons. First, it
is renewable as long as it is properly managed. It is also more evenly distributed over the Earth’s surface than are finite energy sources, and may be
exploited using more environmentally friendly technologies. Biomass provides the opportunity for increased local, regional, and national energy selfsufficiency across the globe.
The energy in biomass can be accessed by turning the raw materials, or
feedstocks, into a usable form. Transportation fuels are made from biomass
through biochemical or thermochemical processes. Known as biofuels, these
include ethanol, methanol, biodiesel, biocrude, and methane.
Ethanol is the most widely used biofuel today. In the United States each year,
more than 1.5 billion gallons are added to gasoline as an oxygenate, to
improve vehicle performance and reduce air pollution. Ethanol is an alcohol,
and most is made using a process similar to brewing beer, in which starch
crops are fermented into ethanol, which is then distilled into its final form.
Ethanol made from cellulosic biomass materials instead of traditional feedstocks (starch crops) is called bioethanol. Ethanol can be used in its pure form
(neat), as a blend with gasoline, or as a fuel for fuel cells.
Methanol is also an alcohol that can be used as a transportation fuel. U.S.
industry produces approximately 1.2 billion gallons of methanol annually,
38% of which is used in the transportation sector. Currently produced using
natural gas, methanol can be produced from biomass through a two-step
thermochemical process. First the biomass is gasified to produce hydrogen
and carbon monoxide. These gases are then reacted to produce methanol.
Methanol can be used in its pure form (neat), as a feedstock for the gasoline
additive methyl tertiary butyl ether (MTBE), or as fuel for fuel cells.
Biodiesel is a renewable diesel fuel substitute that can be made by chemically combining any natural oil or fat with an alcohol (usually methanol).
Many vegetable oils, animal fats, and recycled cooking greases can be transformed into biodiesel and there are many different ways to do it. Biodiesel
can be used neat or as a diesel additive and is typically used as a fuel additive
in 20% blends (B20) with petroleum diesel in compression ignition (diesel)
engines. Other blend levels can be used depending on the cost of the fuel
and the desired benefits.
Biocrude is a product similar to petroleum crude and can be produced from
biomass using a fast pyrolysis process. Biocrude is formed when the biomassderived oil vapors are condensed. Catalytic cracking then converts biocrude
into transportation fuels.
Methane is the major component of compressed natural gas—an alternative
transportation fuel, of which approximately 100 million gallons will be sold in
the United States in 2000. Methane, in a blend of other gases, can be produced from biomass by a biochemical process called anaerobic digestion.
The need for biofuels
S
everal compelling issues drive a national effort to develop and improve
technology to make biofuels. Our dependence on petroleum for fueling
the transportation sector threatens our energy security, affects our environment, and weakens our economy. Developing the technology to produce and
use biofuels will create transportation fuel options that can positively impact
these issues and establish safe, clean, sustainable alternatives to petroleum.
Production of biofuels will create new
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Biofuels for U.S. Energy Security
Perhaps the most important issue surrounding the status of our transportation fuel is that no one knows how long the world’s petroleum resources
will last. Adding to our country's vulnerability, our limited domestic petroleum resources do not meet our energy needs. The Persian Gulf region
holds nearly two-thirds of the world's known oil reserves, and the United
States imports more than 53% of its petroleum—much of it from the Persian
Gulf. The U.S. Department of Energy estimates that this will increase to 75%
by the year 2010. In 1990, Congress voted that a dependence on foreign oil
of more than 50% should be considered a peril point for the United States.
Members of Congress recognize that high levels of imported oil leave our
country defenseless against sudden severe energy disruptions that could capsize our economy. Producing and using fuels from renewable, domestic biomass resources can help ease our dependence on foreign oil imports and
reduce our vulnerability to severe energy disruptions.
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job opportunities for rural Americans
as well as a new market for crops and
agricultural by-products.
Biofuels for the U.S. Economy
Oil imports account for almost half the U.S. trade deficit, which has an enormous impact on our economy and the creation of new jobs. A high trade
imbalance from dependence on foreign oil also leaves our economy vulnerable to price hikes from supply disruptions. Developing a stronger market
for domestically produced biofuels in the United States will help alleviate the
negative implications of our trade deficit and contribute to positive economic
trends in the U.S. transportation sector.
Currently, the ethanol industry is responsible for approximately 200,000
jobs. Between 1996 and 2000, the ethanol industry added approximately
$51 billion to the U.S. economy. Ethanol production creates domestic jobs in
plant construction, operation, maintenance, and support in the surrounding
communities. This can have a profound impact on rural America, where a
decline in employment has placed increasing burdens on our cities, infrastructure, and tax base.
U.S. Petroleum Imports
2010
75%
2000
53%
50% “peril point”
Transportation is a major contributor to
a number of environmental problems,
primarily because of our dependence
on fossil fuels.
By 2010, oil imports are
projected to rise to 75%
of the total U.S. supply.
Biofuels can help reduce
our use of foreign oil.
Agricultural residues and
crops grown for producing energy are major
feedstock sources for
biofuels.
The carbon dioxide released by the
combustion of biofuels is recycled,
Biofuels Recycle
Carbon Dioxide
thereby reducing greenhouse gas
Biofuel
During photosynthesis—
the process used by
plants to grow—carbon
dioxide is absorbed from
the atmosphere. The
carbon that is absorbed
is the major component
of the biomass.
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buildup from fossil fuel emissions.
Biofuels for the Environment
The transportation sector of our country is a major contributor to a number
of environmental problems, primarily because of our dependence on fossil
fuels. From their extraction through their use in automobiles, many steps of
the process either are or can be detrimental to our environment. Producing
and using biofuels for transportation offers alternatives to fossil fuels that can
help provide solutions to many environmental problems.
Biofuels and Global Climate Change
The U.S. transportation sector is responsible for one-third of our country's
carbon dioxide (CO2) emissions. CO2 is considered to be a greenhouse gas,
the buildup of which may lead to global climate change. These emissions
result from burning nonrenewable fossil fuels, which releases their carbon
content into the atmosphere as CO2. Producing and using biofuels for transportation can help reduce CO2 buildup significantly. By displacing the use of
fossi fuels, the emissions resulting from fossil fuels use are avoided, and the
CO2 content of fossil fuels is allowed to remain in storage. Further reductions
occur because the plants and trees that serve as feedstocks for biofuels
require CO2 to grow, and they absorb what they need from the atmosphere.
Biofuels help improve
the air quality of our
cities, pose no threat to
water resources, and
will help alleviate solid
waste disposal issues.
Biofuels and Air Quality
Over the past two decades, our nation has made great strides in improving
air quality in our most polluted urban areas. Biofuels such as ethanol have
been used very successfully as an oxygenate additive in gasoline to reduce
emissions from older, high-polluting vehicles. In the future, as biofuels come
to the forefront as replacements for gasoline, we anticipate further improvements in air quality, whether these fuels are used in conventional internal
combustion engines or in new, clean vehicle technologies such as fuel cells.
Biofuels and Water Quality
Water pollution associated with gasoline includes marine oil spills, groundwater contamination from underground gasoline storage tanks, and runoff
resulting from fuel spills. Biofuels can replace the most toxic parts of gasoline with fuels that quickly biodegrade in water, reducing the threat that
gasoline poses to waterways and groundwater. Spills or leaks of biofuels do
not constitute an environmental hazard.
Biofuels and Waste Disposal
Almost half the landfills in the United States are close to capacity and are
expected to close in the near future. To make matters worse, the rate at
which we produce waste continues to increase. Disposal costs increase as
available landfill space decreases. In addition, some segments of the agricultural and forest products industries produce huge amounts of waste each
year. Much of the waste we produce is made of lignocellulosic material that
can be converted to biofuels. This form of recycling could help relieve our
growing waste problem, while at the same time replace a portion of our
fossil fuel useage.
Research is focused on improving
biomass conversion technology to
lower costs and enable the establishment of a major biofuels industry.
Biofuels on the market
C
urrently, ethanol and biodiesel are commercially available. Ethanol
made from starch crops is available around the country and is commonly used as a fuel oxygenate. Biodiesel is being used by some
municipal fleets around the country and privately in situations where petroleum diesel is detrimental. As knowledge of the economic, energy security,
and environmental benefits of biofuels spread through our country, demand
for these sustainable fuels will increase. To meet the demand and provide
fuels that are competitive with petroleum fuels, national research focuses on
improving technology for converting biomass to fuels. This will decrease
costs, and increase the kinds of biomass that can be converted to fuels,
allowing for a sustainable supply of resources from which to make fuel.
The U.S. Department of Energy leads the National Biofuels Program. The
Program strives to realize the large-scale use of environmentally sound, costcompetitive, biomass-based transportation fuels by adopting and commercializing the best technologies. To accomplish this, the Program works with
industry to research, develop, demonstrate, and facilitate the commercialization of U.S. technologies to develop clean fuels for transportation, leading to
the establishment of a major biofuels industry.
The National Biofuels
Program works to
develop the best technologies in order to
establish a major biofuels industry.
For more information, visit the
National Biofuels Program’s web site at
www.ott.doe.gov/biofuels
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Produced for the U.S. Department of Energy (DOE) by the
National Renewable Energy laboratory, a DOE national laboratory.
DOE/GO-102000-0812 • June 2000
Printed with a renewable-source ink on paper containing at least
50% wastepaper, including 20% postconsumer waste.